A Detailed Guide to the Prevention and Treatment of Orchid Soft Rot

When orchid enthusiasts get together, the topic that draws the most attention is exchangingorchid growingtechniques and discussingorchidcultivationproblems. In recent years, what everyone talks about most is the prevention and treatment ofsoft rotdisease. This disease comes on fast, causes severe damage, has unclear causes, and is difficult to treat. Once it occurs, it is very hard to cure with medication. If decisive measures are not taken in time, it will lead to devastating disaster. Everyone feels thatsoft rotdisease is currently the greatest threat toorchids, and there is a widespread feeling of turning pale at the mention of "rot." For this reason, I have done some investigation into the causes, harm, and prevention ofsoft rot. This cannot be called research, nor can I draw any mature conclusions; I offer these observations to elicit better ideas, for reference only. Causes of soft rot. Some say it is the influence of the potting medium, some say it is caused by watering, and others say it is brought in by re-imported seedlings. The relatively consistent view is that it is a bacterial infection. According to the conclusions of seniororchiddisease experts in Taiwan, China, the pathogen of soft rot is Fusarium, which lives parasitically in the soil and attaches to the pseudobulbs and roots of orchid plants. When orchid seedlings are transplanted or divided, the pathogen invades through the wounds. Therefore, it is often the case that after orchids are divided, or after they have been injured, they are most susceptible to soft rot. From the perspective of climate and season, the temperature suitable for Fusarium growth is 20°C-30°C. It generally grows from April to September, and is most severe from May to August. During this period, combined with other factors such as unclean potting medium with severe contamination and often large amounts of bacteria; poor ventilation in the orchid room, closed for long periods, which favors bacterial reproduction; excessive watering and soggy potting soil, which affects root aeration; improper fertilizing with too much nitrogen fertilizer, causing fertilizer damage; and too little light, making plants weak and lacking disease resistance. Under such conditions, orchid seedlings are more likely to become infected with bacteria and develop soft rot. Once this disease occurs, it spreads rapidly. Often the leaves are just noticed to look abnormal in the morning, and by evening the leaves of the whole plant have turned yellow, with brown spots on the pseudobulbs that expand in a water-soaked manner, then turn black, often with exudate flowing out and giving off a foul odor. For diseased new shoots, a gentle pull lifts them right out; for diseased old leaves, a slight bump breaks them off. If decisive measures are not taken in time to rescue the plant, within a few days it spreads through the entire pot of orchids, causing catastrophic loss. Moreover, through contact such as watering and changing soil, it can transmit the pathogen to other orchid seedlings, with unimaginable consequences. After soft rot occurs, it is very difficult to treat with medication. I have used thiophanate-methyl, carbendazim, chlorothalonil, miconazole, and many other medications for treatment, but the results were all of no avail and could not save the dying diseased orchids. For the prevention and treatment of soft rot, we must adhere to the principle of prevention first and treatment as supplementary. Prevention is active and proactive. Treatment is passive and reactive. Prevention of soft rot: 1. Keep the orchid room clean. In a fresh-air, pollution-free natural environment, orchids are generally full of vitality and rarely suffer from soft rot. But in a closed orchid room, if disinfection is not paid attention to, soft rot very easily occurs. Therefore, attention should be paid to improving the micro-environment fororchid growing, often opening windows, emphasizing ventilation, and preferably having exhaust equipment, so that even when the orchid room is sealed, air can still remain circulating. 2. Water scientifically. First, keep the water clean and do not use bacteria-laden dirty water. Now industry is developing rapidly while environmental protection lags relatively behind. Groundwater in many areas is seriously polluted, and even rainwater is contaminated by dust. It is more convenient to use disinfected tap water, stored for a full day and night to let the chlorine from bleaching powder dissipate before use. Second, use water scientifically according to the condition of the orchid pot; it should be neither too dry nor too wet. If too dry, orchid roots will shrivel and plant growth will be affected. If too wet, roots will rot and bacteria will easily breed. One should keep the potting soil dry but not parched, in a "moist" state. When watering, also pay attention to opening windows for ventilation or using an electric fan to blow air, so that water in the leaf sheaths evaporates in time, avoiding rot at the heart and preventing bacterial infection. 3. Fertilizer must not be too concentrated. Heavy fertilizer will damage roots and cause fertilizer injury; it is better to apply thin fertilizer frequently. When applying chemical fertilizer, mix with water according to the specified ratio, and at the same time match fertilizer elements according to the needs of orchid growth. Organic fertilizer must be fully fermented and, after adding pesticide for sterilization, can then be applied. During high temperatures, apply little or no fertilizer, but a suitable amount of agricultural amino acids may be applied to improve theorchid'simmunity. 4. Spray medication in time for prevention. Generally, every 10-20 days spray agricultural streptomycin or chloramphenicol specifically to kill bacteria. Spray thiophanate-methyl, chlorothalonil, and the like to kill fungi. Apply several pesticides alternately so as not to let pathogens breed and multiply. But note that improper use of medication can produce side effects and bring adverse effects toorchid plants. Long-term use of the same medication can also cause pathogens to develop resistance and lose effectiveness. Treatment of soft rot: Rescue of soft rot must be timely. Usually one should often observe the subtle changes inorchidplants. Once symptoms of soft rot are found - first yellowing of leaves followed by dehydration and withering, and blackening of the pseudobulbs - decisive measures must be taken immediately, the sooner the better, and absolutely not delayed. 1. Immediately cut off the diseased plant and destroy it. When cutting seedlings, observe carefully. If the pseudobulb is seen to have turned brown, continue cutting. If the cut pseudobulb looks fine at the time but after a few minutes shows light brown again, it means bacteria have already infected it, and cutting must continue until the cut surface is completely white. At first, I was eager to save the seedlings and harbored a wishful mentality, always thinking that saving one more plant was better, especially for rare varieties, where I found it even harder to bring myself to act. As a result, the bacteria continued to spread, one plant after another died, leading to "total annihilation." What hurt most was a pot ofCymbidiumrare new variety "Sajin Baozhu," which was lost entirely because the chance for rescue was missed. Later I learned from these painful lessons and steeled myself to part with what I loved. By acting decisively, I instead preserved some good varieties, such as the traditional famous variety Wanzi, the new variety Baohe, the new variety Xinmei, and the striped-leaf dual-art variety. 2. For the surviving orchid seedlings, rinse them clean with water, then soak them in a 0.5% potassium permanganate solution or a 1000-fold agricultural streptomycin solution for 30-60 minutes, then wash them clean again with water, and after drying, repot and plant them. The original potting medium and orchid pot already harbor bacteria and cannot be used again. Replace them with new potting medium and orchid pots that have been disinfected and are free of pathogens. When planting, expose the wound on the pseudobulb outside the potting medium and apply fungicidal powder. Place it in a cool, ventilated spot, and do not water immediately. After three or four days, when the wound has healed and no diseased condition is found, then cover it with potting medium and return to normal management. Shou Jicheng, Zhejiang Home appliance: 0575-6024196 Mobile: 13655755132 Address: Room 232, No. 40 Shengli Road, Chengguan Town, Xinchang County, Zhejiang Province